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How to Build a Computer?
http://www.hardwaretipsandtricks.com/articles/29/1/How-to-Build-a-Computer/Page1.html
By Super Admin
Published on 11/21/2006
 
How To Assemble A Desktop PC.

Choosing the parts

Before you jump onto the web and start spending lots of money on expensive computer parts, there are three important questions you should answer which will guide your purchases:

What will be the main function of the computer?
Will parts be available to use from your old computer--or do you want to reuse parts from your old computer?
How much can you afford to spend on the system?
Often, you will either want to hand your old computer down to someone else, in which case you must keep it functional, or it may be so old that you don't want to use any parts from it, because they will slow down your new machine too much.

What operating system am I going to use?
Before you buy components, be sure that they are supported by the operating system you plan to use. Almost all current, commonly available devices have drivers available for current versions of Windows (generally, anything 2000, XP or newer); if you want to run an alternative operating system, you'll have to do some research -- many alternatives have extensive 'Hardware Compatibility Lists'.

Windows hardware support lists
Windows XP supports most processors and motherboards based on the i386 or x86_64 architectures. Put simply, all available consumer processors (especially from AMD or Intel) will work with the Windows XP operating system.

For other hardware, see Microsoft's compatibility list.

Linux hardware support lists
As one of the most popular free operating systems, Linux is a very good alternative. It has versions for many different architectures, including i386, x64 and PowerPC, though i386 versions are much more common. It will also support all kinds of processors, enabling it to be used on Palm PCs and even iPods. There are many different versions of Linux, produced by different companies these are 'distributions' or 'distros' for short. For a desktop PC, you should make sure to pick a desktop distro, one where the company/organisation has desktop users in mind. e.g. Ubuntu, SimplyMEPIS, Mandriva. SUSE is also a good choice, but also has tools that make it easy to use as a server. Ubuntu has won many awards from PC magazines and is noted for being particularly easy to use (for basic tasks, i.e. Home/Office e.g. web, email, word processing)

All this is important to bear in mind as different distros will support different hardware (generally more 'bleeding-edge' distro will support newer hardware - look at Fedora, SuSE, Ubuntu, but not Debian). A good rule of thumb is to buy hardware that is 12 to 18 months old, as it most probably has Linux support with most distros, but won't be too old.


BSDs hardware support lists
DesktopBSD, see FreeBSD 5.4/i386 and FreeBSD 5.4/amd64
Dragonfly BSD
FreeBSD
NetBSD
OpenBSD
PC-BSD, see FreeBSD 6.0/i386

What will be the main function of the computer?
If you're going to build a computer from scratch for a specific purpose, you'll want to keep that purpose in mind when choosing your components; don't just go to the store or an online shop and start buying components. First, decide what you want to use the computer for. The reason you have to consider this is that you may be able to save money by only specifying expensive, premium components where needed.

Many differing speeds of computer can offer Internet browsing and word-processing capabilities; however, one computer might be faster than another at such tasks. For an office computer, the main components for speed are the processor, memory (RAM), system bus, and hard drive. If the computer is for gaming, the addition of a high-end graphics accelerator expansion card also becomes a major area which greatly affects computing performance and speed.

Simple web surfer
The most important tip is not to go overboard. Basic users can easily get by without the latest gadgets, and although it is easy to get caught up in the hype, you simply do not need to pay a significant amount of money for a computer intended for a new user. A computer used for web surfing and writing the occasional letter does not need to be powerful in any sense, as the speed-limiting steps are invariably the Internet connection speed and the speed at which you can type.
A worthwhile addition to any computer is a basic printer; printed webpages are portable and can be used when the computer is turned off, whether it be a recipe for use in the kitchen or road directions for use in the car. Also, almost everyone will need to print and send letters at times.
A dial-up (56kbps) modem is more than adequate for web browsing, but for users who want to do a lot of web browsing and dowloading large files, a faster modem such as DSL or cable might be preferable.
Server 
If you are going to use your computer as a server (for a lot of clients) you will need to buy lots of RAM, fast hard drives, one or more processors or processor cores, and good network hardware. Graphics and sound are not important. Servers are more availably used in businesses for remote access from clients and kiosks.
Office computer 
For an office computer, you will not need much in the way of graphics or computational power, but you will want to spend more money on interface devices, such as an ergonomic keyboard, a nicer printer, and a larger monitor with a sharp picture, since you may be spending a lot of time using the computer and having to stare at the screen for long periods of time. Also invest in productivity software and a client edition of your operating system (if working from a remote location).
Gaming computer 
On the other hand, somebody who is going to be playing the latest games on their new computer is going to need a lot more graphics power. A powerful graphics card from nVidia or ATI is practically a must. A fast gaming processor such as the Athlon 64 line or Core 2 Duo would be very useful, too. However, they may not want to spend much on computer peripherals such as scanners, printers, or webcameras because they have no interest in such devices. Most newer games require anywhere from 1GB to 4GB of RAM. A DSL or cable internet connection is a necessity for multiplayer gaming - even if you have the fastest computer in the world, a slow internet connection will make it useless for internet gaming.
Workstation 
Some may be more interested in processing large amounts of data. For instance, processing video, rendering, or running computer simulations. In this case the focus is primarily on CPU speed and a common choice is dual CPUs or CPU cores. Gobs of memory is secondary, and a fine RAID hard drive setup can be helpful. Choosing a good motherboard is critical. As is choosing the right amount of RAM (Random Access Memory). Depending on the application, you may need a decent video card. However, most workstation applications will work fine on a value-line video card, since they usually use fairly simple graphics compared to video games. For specific video applications, a video card with specific features may be needed.
Entertainment system 
Here, you'll be most interested in a silent, good-looking case design and, of course, a good monitor. There's a good chance you want to use it as a Personal Video Recorder (PVR) in which case, TV tuner cards, either integrated with the video card or separate, should be selected wisely.

Do I plan on overclocking my computer?
Overclocking is running components of a computer at faster internal speeds than those for which the components were designed. If you plan to overclock your components, some parts respond to overclocking better than others. If you are going to seriously overclock your computer, you need to do extensive research into the components you are selecting. Components that respond well to heavy overclocking are generally not very expensive, although the price of a component is by no means a guarantee of its overclocking potential. It is also important to check your warranties before overclocking. Overclocking sometimes voids your warranty. Overclocking is very risky (you can destroy your entire computer), so be warned! You need to make considerations for cooling the computer as overclocking generates heat. Anything from a few extra fans to a liquid-cooled system may be necessary depending on the nature of your system.

Do I plan on underclocking my computer?
This can be ideal for always-on entertainment systems. Similar considerations as mentioned above for selecting tweakable components. Underclocking allows passive cooling to be used on the underclocked components and results in a silent and energy-efficient system.

The risk here is not destroying your computer, as with overclocking, but instead you may experience problems with hard-disk data integrity. It is a good idea to back up your disk data periodically on a non-volatile medium, such as DVDs or tape.

Can I use any of the parts from my old computer?
The answer to this question is unique in nearly every situation. To start, is your old computer available to take spare parts out of? There are usually several reasons why it wouldn't be.

You want to sell, donate, or give the old machine to a family member.
You want to use your old computer for another use, such as using it as a server of some sort.
Your old computer is too old, or the parts which you wish to reuse are broken, and so will be of no use.
A lot of parts are incompatible with the new computer
In the first situation, you want to sell the old computer. In order to do this, you need to leave in enough parts in order for the computer to function correctly. These include: graphics card (if it's not on the motherboard), hard drive, motherboard, processor, power supply and RAM. However, it is usually a kind gesture to leave, at least, a rudimentary sound card and an ethernet card so the person you are selling your computer to can use a network and play sound and music. Other than these basic parts, you can use the other parts for your new computer if they meet the other criteria above. One important point to remember is that if you are selling your old computer, it is generally a wise idea to erase the hard drive before giving it to it's new owner. Special precautions must be taken to ensure that you are not giving away your sensitive or personal information when you sell your computer. Don't forget that a simple 'delete' command does not actually erase the data on your hard drive. The original data will still be present and can later be recovered by someone else using special programs and/or equipment. To avoid this, programs are available that will effectively 'shred' your data, making it unrecoverable.

Along with using some parts if you are selling a computer, you can also use non-vital parts if you want to use the old computer as a server. For example, if you plan to reuse your old computer as a utility server, you can easily remove parts such as external drives and the sound card, as these have no use in a server, and they can easily be reused in your new computer, if they are of good enough quality and sufficient performance.

Another important fact to remember is that sometimes you may not be able to use old parts because they do not work with your new computer. For example, even if you recently upgraded to a very fast AGP card, if your new motherboard has a PCI-Express 16x slot, you will have to get a new graphics card, as the old card simply won't plug in to the available slot. RAM from your old computer will also often be unusable in your new motherboard.

Since monitor technology moves quite slowly, you can probably keep your current monitor and use it on the new computer, if it's of sufficient size and clarity for your work. The same can go for keyboards (unless you want to upgrade your keyboard to a better model), as well as mice, printers, scanners, and possibly speaker sets. On the inside, you may be able to take out the floppy drive, CD-ROM drive, and possibly the sound card and hard drive (depending on how good they are, of course). Sometimes so much is used from the old computer, that the line between an upgrade and a new computer can become very blurred.

Reusing a hard drive from an older computer is an easy way to keep your data from your old computer, though, with most Windows operating systems, moving a boot drive from one motherboard to another will entail a series of reboots and installation of new drivers; in the case of newer Windows systems, like 2000 and XP, an entire 'refresh install' may be necessary, to allow Windows to install a new Hardware Abstraction Layer.

Where do I find the parts?
Once you have decided what you are going to primarily use your computer for, and you have reviewed which parts are available for reuse, you should make a list of what components you will need to actually build your computer. Always research the best components for your computer's application, and be sure on the exact specifications that you will need, as this will save a lot of time and effort when you start shopping around. Make sure that you understand all terminology related to components before you purchase, as this can also save a lot of confusion later in the process.

There are several places to buy parts:

Internet retailers generally offer the best price for new parts. The main disadvantage occurs if a part is broken and requires returns.
Auction sites offer very good prices for used parts. This is especially useful for parts which do not wear out. As with internet retailers, returns can be problematic.
Local PC shops - Their prices are higher, but they make up for this by providing a lot of expertise.
Big local retailers often have low technical expertise and not very good prices, but are very useful because they can handle returns quickly.
Trade shows that occur from time to time also provide a good place to shop, as the prices are often significantly reduced.
Also, check your local town dump. They may have a special section for computers & monitors that others have gotten rid of. Many times these are more or less brand new computers with such trivial problems as a busted power supply or faulty cables. Of course if the dump does have such a section, it is wise to ask permission of those in charge. They're usually glad to let you go through it, but don't leave a mess. Taking advantage of this can yield incredible finds, with a price tag of free.

OEM vs retail
Most hardware manufacturers will sell the same components for both OEM and Retail computers. Retail hardware is intended to be sold to the end-user through retail channels, and will come fully packaged with manuals, accessories, software, etc. OEM stands for "original equipment manufacturer"; items labeled as such are sold in bulk and are intended for use by firms which may integrate the components into their own products.

However, many online stores will offer OEM hardware at cheaper prices than the corresponding retail versions. You will usually receive such an item by itself in an anti-static bag. It may or may not come with a manual or a CD containing drivers. Warranties on OEM parts may often be shorter, and sometimes require you to obtain support through your vendor, rather than the manufacturer. Other than that, OEM components themselves are usually the same as their retail counterparts.

What should affect the choice of any part/peripherial?
This section lists things that should be taken account of with every single choice when selecting parts. Considering some parts these things are more obvious than with others.

Compatibility
Do your parts and peripherials work together? The three main components that must work together are the CPU, the motherboard, and the RAM. Do they work with the software of your choice? Choosing parts that work with any other operating system than the most mainstream one is often a guarantee that they work with many other operating systems too than just those two. This is good because you can change your mind later. So even if you're building a computer to run Windows, choosing hardware that would run a Linux system might be a good thing. It is also worth checking round the internet to make sure there is no history of your chosen components clashing (eg Motherboards and Graphics cards).

Ergonomics
Ergonomics is most important when choosing peripherals such as keyboard or a mouse, but also the ease of assembly is important when choosing parts.

Ergonomics is the applied science of equipment design, as for the workplace, intended to maximize productivity by reducing operator fatigue and discomfort.

Operating temperature
The computer has to be cooled down so it doesn't overheat and break. Parts with high operating temperatures need more cooling and noiseless cooling is hard to find as well as being far more expensive than their noisy counterparts. Parts and peripherials with high operating temperatures also tend to warm up the room when the system is cooled by air, so the room may need cooling too. Manufacturers assume the computer will be kept in a room that has an air conditioner kept roughly at "room temperature" (≈73F or 22C) but, typically parts are expected to be able to handle more extreme conditions. More heat can tend to decrease stability and increase the elements that break down components slowly over time, so better cooling increases the stability as well as lifetime of your system. Since most of the energy used by a computer is turned into heat, you can tell how much heat a part is generating from the amount of power it consumes.

Price
In the early 80's, desktop computers as compared to modern models were slow, expensive, and mostly limited to businesses and computing hobbyists. However, as time went on, hardware speed and performance improved dramatically while prices steadily decreased. Today, there is a wide array of hardware core components and peripherals tailored to fit every home computing need and budget. Retail outlets, "big-box" electronic stores, and online warehouses offer everything from floppy drives to blazing-fast custom gaming systems built to buyer's specifications.

With all these options to choose from, it can be a bit overwhelming if you've never bought computer parts before. Shop around and compare the prices of both online and retail stores. Remember to factor in shipping and handling, and taxes. Some places may be priced a bit higher, but offer perks such as free shipping, limited warranties, or 24-hour tech support. Many websites, such as CNET and ZDNet offer comprehensive reviews, user ratings, and links to stores, including price comparisons. Although it may be tempting to buy the latest cutting-edge system with all the hottest bells and whistles, you may be able to save a considerable amount of money by purchasing a slightly older computer and upgrading it with a few high-quality peripherals.

Also, keep in mind that components are constantly improving in performance and becoming cheaper to produce, making them less expensive and more available to a wider consumer market. It may pay off to wait until the "hot item" you want comes down in price.

Most importantly, have a clear idea of what you want to use your computer for. It really doesn't make any sense to shell out $500 for a graphics card if you only need your computer for websurfing and email. In short, "Don't pay for features you don't need" is a good rule of thumb when you are shopping for parts.

It may well, however, pay you to think of future upgradeability when selecting some components, this is most true of the motherboard. While the computer that you are building today may be fine for your current needs you will probably need to upgrade it later to meet the ever expanding requirements of some software. So look for a motherboard that will allow you to fit more memory than you are planning to use, preferably without having to replace any of the existing memory. Also look for support for recent standards of connection to other equipment, e.g. you may be going to use a cheap IDE hard drive at the moment but later you will possibly need to upgrate to a larger, faster,SATA drive - so get a motherboard that supports both. It is always a good idea to have some spare slots for both memory and interface cards - if you are currently using all the facilities it is possible to fit to a machine the only possible upgrade is often another new machine.

You may also find that by overspecifing in some areas you can save money on others, e.g. if you don't currently need fantastic sound but you do need firewire then some of the higher end sound cards also have a firewire port.

Power
The speed of a processor, the size of memory, resolution of monitor, the output of cooling fans, printer or a scanner. Find out what is enough and look for the best price/quality-relation matching your need and budget.

Primary Components
These are the components that will be the core of your new computer. It is impractical to put together a PC compatible computer without these components and a bare set of peripherals.

Chassis (case) & power supply
The case was probably the most overlooked part of the whole computer at one stage. Most cases were beige, and since most components drew far less power than similar components do now, power supplies were never talked about. Recently, however, cases have become considerably more attractive, and people spend a sizable amount of their upgrade budgets on lights and glow-in-the-dark cables. Cases now come in millions of styles, and colours to suit anyone's taste.

People are spending more money on cases now than they ever have before. If you are only building an office computer, the style of case will be of little concern to you, so you might only want a inexpensive ATX case (ATX is the specification which makes them the same size, so you can put the same parts inside), and an inexpensive power supply, since you won't be running high-end processors or high-end graphic cards. Keep in mind not to buy a power supply with a sleeve bearing fan, as these are of considerably less quality. As a guide, you will not want a power supply with a rating of less than 300 watts, as you may likely not be able to power all the parts in your computer with a power supply with a lower rating. Most case-power supply bundles are adequate, but tend to be of a lower quality than power supplies that are sold separately from cases.

For a quiet system, you may want to choose a fanless power supply -- more expensive but well worth it if noise is a concern.

For cases and power supply there are 5 things to consider.

Formfactor
For general use, the ATX formfactor is recommended because it allows your computer to be easily expanded, and is the most common standard formfactor for computers.

ATX In this form factor the motherboard is vertical for more space and more efficient cooling.
Micro ATX is smaller than vanilla ATX, but at the cost of fewer expansion slots. Flex ATX is even smaller than Micro ATX, but only allows 2 expansion slots.
WTX is intended for workstations and servers.
BTX is another formfactor designed for more efficient cooling.
PicoBTX 8"x10.5"
'MicroBTX up to 10.4"x10.5"
BTX up to 12.8"x10.5"
Mini-ITX is even smaller than BTX, at 6.75" square.
NLX
Many OEM computers use non-standard formfactors. Be sure to choose a motherboard compatible with your case's formfactor.

Number of storage drive spaces
Internal hard drives/floppy drives (which go in the small 3.5" bays) and internal DVD drives (which go in the large 5.25" bays) take up space in the case, so make sure you consider how many drives you have. It is usually a good idea to calculate the number of drive spaces needed using your motherboard requirements as a baseline minimum.

Number of IDE x2
Number of FDD x2
Number of SATA
Number of SCSI2 (estimated)
e.g. For a motherboard with one FDD, one IDE, 4 SATA no SCSI. It is often best to choose one with at least 8 slots.
4 BIG + 4 SMALL = 4 optical drives + 3 hard drives + 1 floppy drive
This is the mid-tower configuration. For smaller computers with less storage drives, like 1 hard drive and 2 optical drives, get a mini-tower (2 BIG + 2 SMALL) because it saves space.

Note that it's possible to buy adaptors to fit items that go in small bays (usually hard drives) into large bays. It is however not possible to do the reverse.

Power rating
A too small power number doesn't run your high power devices (like optical, CPU and Graphics Cards). For certain graphics cards (especially high end ones with dual expansion slots), a recommendation of 450W is required. In general, if your motherboard has a 24 pin power connector, choose one which is at least 350W as the 4 extra pins are for high power applications. Also, you would want a PSU with dual 12 volt rails rated together for at least 30 amps. When in doubt, buy a more powerful PSU.

Choose an efficent PSU. Efficient PSU runs cool and quiet and thus do not cause much noise (important if you plan to sleep in the same room with it or using it as a media centre PC)

Note: Intel Pentium 4/D/EE have high power requirements, a 300W PSU is recommended.

Fan
Some cases have case fans. Make sure to choose one which matches your CPU interface on the motherboard. The best option is to purchase a 4-pin Molex connector fan as some motherboards do not have three pin fan ports. Although most motherboards fit most cases, it is the position of the case fan that affects speed and stability of the system. A good case has the fan aimed directly at the CPU for best results.

Aim to choose fans which are quiet. Usually larger fans run slower and produce less noise (and thus more efficient).

Aesthetics and power
If you plan on building a high end gaming PC, you might want a case that looks good, and a much more potent power supply. For the more aesthetically inclined, there are countless companies who make designer cases that will suit many personal preferences. A power supply with more than 400 watts is usually more than is required by most people, and will allow you to power high-end graphics cards, cooling systems, and aesthetic enhancements such as cold cathode lights, cooling equipment, and other such things.

In all cases you should try to check reviews from a computer hardware site before you decide to purchase a power supply; quality can vary greatly and wattage output is frequently overstated. Quality power is also usually more efficient, so it will produce less heat and its fans can run at lower, quieter speeds. Manufacturers sometimes try to make passive, or fanless, power supplies, but in most cases they will end up running dangerously hot, and so are only suitable if you plan to add your own cooling solution.

CPU (processor)
The Central Processing Unit (CPU) is the heart of your computer as it performs nearlly all functions that require extensive processing power. Therefore, it is very important that you choose a suitable CPU for your function as the choice of CPU directly affects the speed and stability of your system.

Before we can explain differences between CPUs, you must first be familiar with certain CPU properties.

Clock speed 
Clock speed, measured in Gigahertz (GHz), (or Megahertz (MHz) on older systems) is the number of calculation cycles that your CPU can perform per second. Therefore, a higher clock speed generally points toward a faster system. But not all CPUs perform an equal quantity of work per cycle, meaning two CPUs at the same clock speed can potentially perform at very different levels.
IPC 
IPC, or instructions per cycle, is the amount of work a CPU can do in a cycle. This varies with different properties of the CPU.
Front side bus speed (FSB) 
Front side bus speed is the rate at which the CPU communicates with the northbridge chipset component on your motherboard in MHz. A larger FSB value shows that your CPU is able to communicate with other components on the motherboard (and thus your system) faster.
Interface (Socket/Slot) 
CPUs must connect to motherboards via a series of connectors. It is VERY important that your CPU interface is a COMPLETE MATCH to your motherboard CPU socket otherwise you would be wasting money on a piece of spare silicon.
Bit-rate 
Most modern CPUs are of the 32-bit system which work fine with most modern operating system and hardware. Higher end models are the 64-bit system which may allow faster CPU processing capabilities due to the larger band-width, but not all operating systems are compatible with the newer 64-bit format -- they will still run, but without a major performance boost. You will require 64-bit if you require to manage more than 4GB of RAM.
Cores and Hyperthreading (HT):

Dual-Core Advantages
Dual-core processors are a fairly new innovation built by both major processor manufacturers (Intel Core Duo / Core 2 Duo and AMD Athlon 64 X2).

Multitasking: Each processor has two processing centres (cores) for (a theoretical maximum of) twice the operating power and for better multitasking. Major advantages of dual core processors are evident when doing heavy multitasking, such as encoding video and playing video games at the same time.
Application Support: Newer applications are being written to take advantage of this technology by using a technique known as Multithreading.
Power Saving: Dual core processors (especially Intel Core Duo) have the ability to turn off one of its cores when application demand is low to save power.

Disadvantages
Support: Older programs with certain notable exceptions) do not support multithreading and may run slower on dual core CPUs.
Price: Dual core processors are also significantly more expensive than their single core brethren

Multi-core Future?
However with quad core technology around the corner, and more and more programs being built to take advantage of multiple cores, the prices are sure to decrease, and the availability and usability of dual core processors is sure to increase greatly.

Hyper-threading (HT) 
Hyper-threading is a technology which allows a single core processor to simulate having two cores, giving a performance boost when running several programs at once. It requires motherboards and chipsets supporting Hyper-Threading technology. It also suffers similar disadvantages as Dual-Core Processors of support and price.
Cache 
Cache is the amount of Memory dedicated for the CPU in MB. Generally, the larger the cache, the faster your system would run. However, cache uses a lot of transistors, and the larger the cache, the higher number of transistors needed, which consume more electricity, and output more heat. Cache comes in (usually) three varieties, L1, L2, and L3. L1 being the smallest and fastest, and L3 being the largest and slowest. Usually only the L2 cache size will be shown, as L3 is rarely used in processor design, and L1 will often stay the same size throughout an entire processor product line.
Core 
The Core of the CPU is the heart of the CPU. Often several cores will be marketed under the same name, so look at what core you are buying.
Now, one of the most common mistakes of choosing a CPU is by ignoring the fine print of CPU specifications while relying completely on the clock speed. CPUs specs are written in full:

Intel Pentium 4 3.2GHz LGA775 FSB800 HT L2-2MB
Model: Intel Pentium 4
Clock Speed: 3.2GHz (=3200MHz)
Interface: Land Grid Array 775
L2-Cache: 2MB (=2048 kB)
Frontside Bus: 800 Mhz
Other Spec: HT technology
The consumer logic for processor speed may be misleading because many consumers think that clock speed, which is measured in gigahertz (GHz) or megahertz (MHz) is equal to system speed. While the higher the clock speed the CPU is able to do cycles more frequently and it does have a fundamental effect on speed, it is not the sole factor as the number of calculations per cycle is different for each different manufacturer and model.

Intel classifies its CPUs using a series of numbers. 3xx, 4xx, 5xx, 6xx and 7xx of which 7xx being the highest end products. Generally, the higher the number, the faster the CPU and the more expensive. usually, models and ratings correspond.

3xx Series: Intel Celeron (L2-128KB)
4xx Series: Intel Celeron D (L2-512KB)
5xx Series: Intel Pentium 4 / Celeron D (L2-1MB)
6xx Series: Intel Pentium 4 / Pentium 4 XE (L2-2MB)
7xx Series: Intel Pentium 4 XE
8xx Series: Intel Pentium D
9xx Series: Intel Pentium D
The number followed by suffix J signifies XD technology.

e.g. Intel Pentium 4 3.0GHz L2-1MB with HT --> Intel Pentium 4 530J
AMD CPUs are even more confusing in classification. The AMD Athlon CPU rating are not of the actual clock speed but rather the equivalence bench mark performance corresponding to a comparison to the AMD Athlon Thunderbird 1.0Ghz. The conversion Table is as follows:

AMD Athlon 1500+ = Actually runs at 1.33 GHz
AMD Athlon 1600+ = Actually runs at 1.40 GHz
AMD Athlon 1700+ = Actually runs at 1.47 GHz
AMD Athlon 1800+ = Actually runs at 1.53 GHz
AMD Athlon 1900+ = Actually runs at 1.60 GHz
AMD Athlon 2000+ = Actually runs at 1.67 GHz
AMD Athlon 2100+ = Actually runs at 1.73 GHz
AMD Athlon 2200+ = Actually runs at 1.80 GHz
AMD Athlon 2400+ = Actually runs at 1.93 GHz
AMD Athlon 2500+ = Actually runs at 1.833 GHz
AMD Athlon 2600+ = Actually runs at 2.133 GHz
AMD Athlon 2700+ = Actually runs at 2.17 GHz
AMD Athlon 2800+ = Actually runs at 2.083 GHz
AMD Athlon 3000+ = Actually runs at 2.167 GHz
AMD Athlon 3200+ = Actually runs at 2.20 GHz
You may wish to purchase a high end AMD64/EM64T (from Intel) processor, which provides support for 64-bit operating system (eg. Windows XP Professional 64-bit Edition). A 64-bit system is very efficient in handling large amounts of RAM. A 32-bit system efficiency drops beyond about 512 to 864MB of RAM, and becomes significantly less efficient beyond 4GB of RAM. Most processors for gaming range in about the 2.8Ghz-3.2Ghz

A 64-bit processor is currently an expensive investment as most applications run on the 32-bit system. However, there is no doubt that the 32-bit system would gradually be replaced by the 64-bit system when the prices fall over a few years time. It is unlikely that the 64-bit system would completely replace the 32-bit system within 5 years but Linux users might find a great improvement in speed when a 64-bit processor is used. Note that there are processors that can run 32-bit code and 64-bit code; they are becoming very popular and may prove a very wise investment for the future of computing, which will invariably be 64-bit. They are more expensive than processors that only run 32-bit code; however, it should be noted that AMD has invested in this market faithfully, and therefore all of their processors, even their low-end Sempron line, runs both types of code. The same cannot be said for the Intel family, which only includes such technology in their high-end server processors and the majority of their desktop line in what is called "EM64T", or Extended Memory 64 Bit Technology. This is an advantage to purchasing an AMD processor.

Smaller processors are generally preferred for overclocking, as they run cooler, and can achieve higher clock speeds. Retail CPU's come in a package containing a HSF (Heat Sink Fan), instructions, and a warranty, often 3 years. OEM CPUs do not include these.

The current CPU speeds and advantages change frequently, so for up-to-date comparisons, you may want to check a website that specializes in Hardware reviews, such as Tom's Hardware Guide or Anandtech. A current (as of 14 February 2006) beginner's explanation can be found at Behardware.

CPU cooling
CPU cooling is very important and should not be overlooked. A less than average CPU temperature prolongs CPU life (up to more than 10 years). On the other hand high CPU temperatures can cause unreliable operation, such as computer freezes, or slow operation. Extremely high temperatures can cause immediate CPU destruction by melting the materials in the chip and changing the physical shape of the sensitive transistors on the CPU. Because of this, never switch on the computer if your CPU has no cooling at all. It is an extremely stupid thing to do, the scenario of "I'll just test whether my CPU works!" as by doing so, you would find that the CPU fries in less than 5 seconds and you will be off to buy a new one.

Most CPU installations use forced-air cooling, but convection cooling and water cooling are also options. For traditional forced-air cooling, the heat sink and fan (HSF) included in most retail CPUs is usually sufficient to cool the CPU at stock speed. Overclockers might want to use a more powerful aftermarket fan, or even try water cooling because they need additional cooling ability given the increased heat of overclocking.

HSFs with decent performance are usually copper-based. The cooling effect is enhanced if the HSF has heatpipes. Silent (i.e. fanless) HSFs are there to provide users a nearly silent cooling.

Many retail heatsink+fan units have a thermal pad installed, which transfers heat from the CPU to the fan helping diffuse the heat created by the CPU. This pad is usable only once. If you wish to remove the fan from another CPU so that you can use it on your new one, or need to take it off for some reason, you will need to remove it, and apply a thermal paste or another thermal pad. Note that some of the cheaper pads can melt in unexpected heat and may cause problems and potentially even damage if you are overclocking. In either case, thermal paste is usually more effective, just harder to apply. If you plan to do any high performance computing, or removing and replacing the HSF, often thermal paste is suggested. If you are planning a long term installation a thermal pad is suggested. Non-conductive thermal pastes made up of silicon are the cheapest and safest.

Silver-based thermal pastes sometimes perform better than normal thermal pastes, and carbon-based ones perform better still. When applied improperly both can be conductive, causing electrical shorts upon contact with the motherboard. A thin properly-applied layer will usually prevent this problem, though some pastes can become runny when they get hot. Users should also beware that many "silver" thermal pastes do not actually contain any silver metal.

For quiet operation, start with a low-heat (low number of watts) CPU. Processors made by VIA, such as the VIA C3, tend to produce low amounts of heat. The Pentium M gives performance that is on par with many of the desktop processors, but gives off more heat than the Via processors. You can also underclock your CPU, giving up some unneeded performance for some peace and quiet. Another option is to choose a large copper heat sink with an open fin pattern. However, true fanless operation is difficult to achieve in most case designs. You can position a case fan to blow across the heat sink, or mount a fan on the heat sink. With either choice of fan placement, choose a large and slow fan over a small and fast fan to decrease noise and increase air flow.

Some low-noise CPU cooling fans require special mounting hardware on the motherboard. Be sure that the cooling fan you choose is compatible with your motherboard.

Motherboard
It cannot be over stressed that the motherboard is the MOST important part of your computer. It is worth investing in a decent motherboard rather than a CPU (although if financially acceptable, both) as your motherboard is what connects different parts of the computer together. In addition, the difference between a cheap and a quality motherboard is typically around $100. A good motherboard allows a modest CPU and RAM to run at maximum efficiency whereas a bad motherboard restricts high-end products to run only at modest levels. A high quality motherboard can go for $200 U.S. or more.

There are 6 things one must consider in choosing a motherboard, CPU Interface, Chipset, IDE or SATA support, Expansion Slot Interfaces and Other Connectors.

CPU Interface
The CPU interface is the "plug" that your processor goes into. For your processor to physically fit in the motherboard, the interface must be an exact match to your processor. Intel currently has two mainstream formats, the older Socket 478 (which is gradually being phased out) and the newer Land Grid Array 775, which supports higher end CPU with HT technology due to its more efficient transfer rate. AMD currently uses three sockets, AM2, 754 and 939. New AM2 sockets are faster (compatible with DDR II RAM) and more efficient than the older two. Socket 754 was aimed at the value market, while Socket 939 was for performance applications.

To ensure that the processor has the correct interface as the motherboard supports, the vendor would typically list this information on its specifications.

Formfactor
You must choose a case that your motherboard can fit inside of. A MicroATX motherboard will do, mostly because it can fit, and it fits many type of CPU sockets, while an ATX motherboard is also viable. Other choices such as MiniITX and NanoITX may also be considered for small form factor or home entertainment computers. The new BTX form factor may be used by enthusiasts. Note that much of the time, an ATX case can contain Micro-ATX motherboards.

Chipset
Chipsets are also important as it determines the efficiency of RAM and Expansion slots

Intel 915 supports up to 533MHz PC4200 DDRII RAM
Intel 925 supports up to 600MHz PC4800 DDRII RAM
All currently existing and in AMD formats currently use DDR RAM, with the standard 400MHz PC3200 being most common. Most Intel socket 478 processors also use the older DDR RAM

The functions of BIOS is highly important. Some BIOS features crash proof functions essential for updating the firmware. Other motherboards allow BIOS control of overclocking of CPU, RAM and Graphics card which are much more stable and safer for overclocking. Newer BIOS have temperature controls, and functions that shut down the computer if the temperature gets too high.

IDE (ATA) or SATA interface
Older PCs have the two IDE interface which are parallel 44 pin connectors but as the motherboard cannot access two devices connected on the same IDE port simultaneously, this has caused a drawback in speed of hard drives and DVD-drives. The newer serial ATA (SATA) interface has 4 separate slots that allow independent access and thus increases the speed of which hard drives work.

Expansion slot interfaces
Old motherboards may have one or more the following slots:

AGP - for graphics cards (ranging from AGP 1x, 2x, 4x and 8x)
PCI - for expansion cards and obsolete low end graphics cards
Note that some graphics cards that run on PCI interfaces are not always obsolete. ATI still manufactures PCI graphics cards, but for better performance try a card supporting PCI-Express. AGP is not a good idea, becuase it requires specific steps to set up, and the drivers, if not updated, do not support the card. You may come upon ancient motherboards with neither AGP or PCI, but please don't waste your time trying to reuse them.

Due to the evolution of new graphics cards on the serial PCI-Express Technology, current newer motherboards have the following connections:

PCI-Express 16x for mainstream graphics cards (4 times speed of AGP 8x)
PCI-Express 1x for faster expansion cards (replacing older PCI)
PCI for use of old expansion cards (would be phased out)
Older AGP 8x graphics cards are generally being phased out for PCI-Express 16x, as the speed and efficiency is about 4 times that of the AGP 8x technology. Old PCI cards are either now built into the motherboard (for sound cards, LAN cards, IEEE 1394 firewire and USB 2.0 interfaces) or becoming PCI-Express variants.

Other Connectors
Some considerations for other connectors and expansions include

USB - the number and version of USB connectors (USB 1.0, 1.1 or 2.0)
On-Board Sound Card - Stereo, 3.1, 5.1, 6.1, 7.1, 8.1
On-Board Graphics Card (Phasing Out)
On-Board Base 100 LAN Card
Serial COM or Parallel Printer Ports
On-Board IEEE 1394 Firewire
At least 6 USB 2.0 ports are recommended for high speed access. On-Board Graphics cards are generally becoming obsolete as they cannot match the newer PCI-Express 16x technology, especially for gaming where high cooling and efficiency is required. USB ports sometimes can come bundled into the front of your computer case for easier access. (Most on-board graphics chipsets are Intel's Extreme Graphics (2), a very obsolete graphics interface.)

Modern motherboards usually come with onboard sound, which is more than enough for the average user. If you are particular about audio quality or plan to use your computer to record high-end audio, you may prefer to use a dedicated sound card (preferably PCI-Express 1x). Some high-end motherboards support on-board 5.1 Channel Dolby surround sounds so this may also be a consideration.

Onboard graphics are very acceptable for anyone not playing performance demanding 3D games or using 3D graphics applications such as Computer Aided Drafting (CAD). Onboard graphics will use a small amount of system RAM as graphics memory (often called shared memory). Purchasing a motherboard with a built-in graphics card is an easy way to save money for an office computer.

If you want gigabit Ethernet capabilities, you should purchase a motherboard with the feature built in. By being built into the motherboard, it will have a faster link to all your components than it would through a PCI expansion card. Also, if you'd like to import Digital Video (DV) onto your system, many higher-end motherboards offer onboard FireWire ports.

If you are upgrading an older computer, keep in mind the motherboard's number and type of expansion board slots.

RAM (random access memory)
The amount of RAM you use is dependent on the purpose that you want to use it for. Older versions of Windows and Linux will run comfortably, though slowly at times, on 128 MB. Some newer operating systems such as Windows XP require 256MB of RAM to run. Many people now have 512 MB or more for better performance. Users of modern games and graphics software, or people who may wish to host Internet services such as a Web site, may want 1 GB or more.

Another thing to consider when choosing the amount of RAM for your system is your graphics card. Most motherboard-integrated graphics chips and PCI Express graphics cards marketed with the "Turbo Cache" feature will use system memory to store information related to rendering graphics; this system memory is generally not available at all to the operating system. On average, these graphics processors will use between 64MB and 512MB of system memory for rendering purposes.

The actual type of RAM you will need will depend on the motherboard and chipset you get. Most current motherboards use DDR (Double Data Rate) RAM. The Intel 915/925 chipsets use DDR2 RAM. Chipsets that use dual-channel memory require you to use two identical (in terms of size and speed) sticks of RAM. Your RAM should usually operate at the same clock speed as the CPU's Front Side Bus (FSB). Your motherboard may not be able to run RAM slower than the FSB, and using RAM faster than the FSB will simply have it run at the same speed as your FSB. Buying low-latency RAM will help with overclocking your FSB, which can be of use to people who want to get more speed from their system.

If you are upgrading from an existing computer, it is best to check with a user group to see if your machine requires specific kinds of RAM. Many computer OEMs, such as Gateway and HP, require custom RAM, and generic RAM available from most computer stores may cause compatibility problems in such systems.

RAM have different bandwidths, ie 400, 533, 600, 733, 800, the current trend is moving from DDR2-400 RAM to DDR2-533 RAM as it is more efficient. Higher end models are very expensive unless you find it worth the investment.

Labeling of RAM
RAM are labelled by its Memory Size (In MB) and clockspeed (or bandwidth).

SDRAM (Synchronous Dynamic RAM) is labeled by its clock speed in megahertz (MHz). For example, PC133 RAM runs at 133MHz. SDRAM is nearly obsolete as nearly all motherboards have withdrawn support for SDRAM. It is now superceded by the more efficient DDR RAM.

128MB SD-133 = 128MB PC133 RAM
DDR RAM can be labeled in two different ways. It can be labeled by approximate bandwidth; as an example, 400MHz-effective DDR RAM has approximately 3.2GB/s of bandwidth, so it is commonly labeled as PC3200. It can also be labeled by its effective clock speed; 400MHz effective DDR RAM is also known as DDR-400. There is also DDR and DDR2 labelled as PC and PC2.

256MB DDR-400 = 256MB PC 3200 RAM
256MB DDR2-400 = 256MB PC2 3200 RAM
DDR RAM has two versions DDR (also DDRI) and DDR2 (or DDRII)

DDR supports DDR-200, DDR-266, DDR-333, DDR-400 (mainstream) and DDR-533 (rare)
DDR2 supports DDR-400, DDR-533 (mainstream) and rare/expensive DDR-667, DDR-800, DDR-1066

Hard drive
Things to consider when shopping for a hard drive:

Interface
The interface of a drive is how the hard drive comunicates with the rest of the computer. The following hard driver interfaces are avalible:
IDE cables can be distinguished by their wide 40-pin connector, coloured first-pin wire, and usually white "ribbon" style cables. This technology is rapidly deteriorating, as it cannot keep up with the increasing speed of current hard drives. IDE based hard drives do not exceed 7,200 RPM.
SATA drives reach up to 10,000 RPM. If you want Serial ATA, you will either need to purchase a motherboard that supports it, or purchase a PCI card that will allow you to connect your hard drive. Note that only certain motherboard implementations will allow you to install Windows XP to a Serial ATA hard drive.
SCSI, although more expensive and less user friendly, is usualy worthwile on high performance workstations and servers. Few consumer desktop motherboards built today support SCSI, and for building a new computer, the work needed to implement it may be outweighed by the relative simplicity and performance of IDE and SATA. SCSI hard drives can reach rotational speeds of up to 15,000 RPM, though these are generaly prohibitively expensive.
USB or IEEE1394 can be used for connecting external drives. An external drive enclosure can convert an internal drive to an external drive.
Cache 
The cache of a Hard drive is a faster media than the hard drive itself, which is normally 2MB (in low-end), 8MB (standard), or 16MB (large disks only) large. The existence of a cache increases the speeds of retrieving short bursts of information, and also prefetches data. Most modern hard drives have 8MB cache, improving performance with a relatively small price difference when compared to 2MB.
Formfactor
3.5 inches is usually used in desktops.
2.5 inches is usually used in laptops.
Capacity 
As a rule-of-thumb minimum, you will need a hard drive capable of holding at least 20GB, although the largest drives available on the market can contain 1TB (1000GB). Few people will need disks this large - for most people, somewhere in the range of 80-200GB will be sufficient. The amount of space you will need can depend on many factors, such as how many high-end games and programs you want to install, how many media files you wish to store, or how many high-quality videos you want to render. It is usually better to get a hard drive with a capacity slightly larger than you anticipate using, in case you need more in the future. However, should you run out of space, you may add an additional hard drive if you have any free IDE or Serial ATA connectors, or through an external interface, such as USB or FireWire.
Rotational Speed 
The speed that the hard drives platters spin at. However drives above 7,200 RPM usually have limited capacity, and a much higher price than 7,200RPM drives of the same capacity, making drives above 7,200RPM not ideal for the desktop.
Warranty 
Many manufactures offer warranties ranging from 30 days (typically OEM) up to five years. It is well worth spending an extra few dollars to extend the drive warranty as long as possible.

Secondary components
These components are important to your computer, but are not as central and necessary as the Core Components.

Video output
For a computer to use a display for monitoring it will need some form of video card into which a display can be plugged. The majority of home and office computers, which predominatly use 2D graphics for office applications and web surfing can use an 'onboard' or integrated graphic processor which will be included on most low to mid range mainboards. For building a computer for gaming, or 3D modelling, a good quality graphics card will be needed.

Currently, two companies dominate the 3D graphics accelerator market nVIDIA and ATI. nVIDIA and ATI build their own graphics products, and license their technologies to other companies. Each brand's similar models have comparable performance levels, and each brand has its own supporters. Video cards have their own RAM, and many of the same rules that dominate the motherboard RAM field apply here: the more RAM, and the faster it is, the better the performance will be. Most applications require at least 32MB of video RAM, although 128MB is rapidly becoming the new standard. On the other end, 512MB video cards top the consumer end of the video card market. As a rule of thumb, if you want a high end video card, you need a minimum of 128MB of video memory -- preferably 256MB. Don't be fooled, though; memory is only part of the card and the actual video processor is more important than the memory. It is important to understand that an integrated graphics card uses the system's RAM, and relies heavily on your system's CPU. This will mean slow performance for graphic-intensive software, such as games.

It is generally better to choose your video card based on your own research, as everyone has slightly different needs. Many video card and chip makers are known to measure their products' performances in ways that you may not find practical. A good video card is often much more than a robust 3D renderer; be sure to examine what you want and need your card to do, such as digital (DVI) output, TV output, multiple-monitor support, built-in TV tuners and video input. Another reason you need to carefully research is that manufacturers will often use confusing model numbers designed to make a card sound better than it is to sell it better. For example, the Geforce 4 MX series of cards claim to be a "Geforce 4," however, the actual processor is closer to a Geforce 2, only more powerful, meaning that these cards actually lack many features available even to the Geforce 3 series. However, when these cards were first produced, they were considerably cheaper than a real Geforce 4 (the TI series) making them an ideal choice if you were more interested in working on a spreadsheet than in playing games. For this sort of reason, you have to carefully pick your card depending on your needs. TV outputs can easily be adapted to your computer by using a DVI - Component Video cable.

Newer technologies such as SLI allow the use of two video cards to render the same video scene, similar to using two CPUs or a dual-core CPU. These systems tend to be very expensive, as only the latest video cards offer this option, and you'll need two of them. However, it can be a useful upgrade path to consider. A SLI-capable motherboard is usually not much more expensive than the regular model, and will work fine with a single video card. You can use it with one card now, and buy another one in the future (which will probably be much cheaper by then), which means you will take advantage of your old video card too.

Interface
There are four different graphics card interfaces: integrated, PCI, AGP and PCI-Express.

Most retail computers will ship with an integrated graphics card. This means that if you are looking at playing games you will need to upgrade. Most mainboards that have integrated graphics will also have one of the other three interfaces so it isn't hard to place a new card to suit your needs if the need ever arises.

Old video cards use the standard PCI slots that are now obsolete due to limited speed and memory. PCI cannot transfer data very quickly, so a system with such a card will often seem to "jump" or halt for short periods when data is being transfered. These cards are needed for a few rare systems lacking an AGP slot (usually low end desktop systems designed to be cheap.) They are also useful for adding aditonal video cards to a system.

Most video cards bought in the last 2 years are of the AGP standard. There are 4 different speed and bandwidths of AGP, 1x, 2x, 4x and 8x. While 8x is the fastest and most common for high end products, the true performance of your AGP card is limited by the lower AGP value of your graphics card and motherboard. For example, an AGP 8x card on a 4x motherboard can only run at up to 4x. AGP will be phased out and there will not be an AGP 16x due to technical limitations, and size necessarily.

The newest trend in graphics card is the PCI-Express (not to be confused with PCI-X) system that supports up to 16x speeds. This is new technology and is generally more expensive but it runs at higher speeds. Some newer graphics cards come in both AGP and PCI-E 16x models, such as the Radeon x800 and the GeForce 6800 series. The newest models of graphics cards, such as the GeForce 7800 and the Radeon X1800, are only made for the PCI-E 16x. (Most motherboards have only one PCI-E 16x while having plenty of PCI-E 1x slots... so make sure you use the right one.) Motherboards with 2 PCI-Express 16x slots can combine the power of 2 video cards using technologies known as SLI for NVidia, and CrossFire for ATI. However, you will have to match the video cards to a motherboard supporting the multiple card technology of choice, and use two similar video cards that both support dual video cards.

Keep in mind that to provide best picture quality and to prevent scaling, your graphics card must be capable of displaying same resolution as your LCD display's native resolution.

CD/DVD
Optical drives have progressed a long way in the past few years, and you can now easily purchase DVD writers that are capable of burning 9GB of data to a disk for an insignificant amount of money. Even if you don't plan on watching or copying DVDs on your computer, it is still worth purchasing a burner for their superior backup capabilities.

When purchasing a DVD writer, you will want one that is capable of burning both the '+' and '-' standards, and they should also be Dual Layer compatible. This will ensure that you can burn to almost all recordable DVDs currently on the market (the other major format, DVD-RAM is almost unused, for the most part, so don't worry about it).

Floppy drive
Though generally not needed, floppy drives are often installed anyway. Floppy drives have been made obsolete in recent years by devices such as USB "Thumb Drives" and CD writers. Floppy drives are sometimes required for BIOS updates and exchanging small files with older computers. Floppy drives block air movement with wide cables, and can make computers set to check the drive take longer to start (most have an option in their bios to disable this.) The drives and disks are also notoriously unreliable. One option to overcome the cable problem and to make it easier to install is to buy an external USB floppy drive. These are potentially a little bit faster and can be plugged into a different system (such as a laptop without a floppy drive.) However, not all systems support booting from a USB floppy drive -- most notably older motherboards. Most newer systems do now though. A USB floppy drive is considerably more expensive and since floppy drives are not needed much anymore, this is rarely a useful option. You can easily get a thumb drive holding more than 50 times as much as one floppy disk for the same price as a USB floppy drive.

Sound card
Most motherboards have built-in sound features. These are often adequate for most users. However, you can purchase a good sound card and speakers at relatively low cost - a few dollars at the low end can make an enormous difference in the range and clarity of sound. Also, these onboard systems tend to use more system resources, so you are better off with a real soundcard for gaming.

Good quality in sound cards depends on a few factors. The digital-analog conversion (DAC) is generally the most important stage for general clarity, but it is a poorly measurable process. Reviews, especially those from audiophile sources, are worth consulting for this; but don't go purely by specifications, as many different models with similar specs can produce completely different results. Cards may offer digital (S/PDIF) output, in which case the DAC process is moved from your sound card either to a dedicated receiver or to one built into your speakers.

Sound cards made for gaming or professional music tend to do outstandingly well for their particular purpose. In games various effects are oftentimes applied to the sound in real-time, and a gaming sound card will be able to do this processing on-board, instead of using your CPU for the task. Professional music cards tend to be built both for maximum sound quality and low latency (transmission delay) input and output, and include more and/or different kinds of inputs than those of consumer cards.


Choosing the parts

Modem
A modem is needed in order to connect to a dial up internet connection. A modem can also be used for faxing. Modems can attach to the computer in different ways, and can have built-in processing or use the computer's CPU for processing.

Modems with built-in processing generally include all modems that connect via a standard serial port, as well as any modems that refer to themselves as "Hardware Modems". Software Modems, or modems that rely on the CPU generally include both Internal and USB modems, or have packaging that mentions drivers or requiring a specific CPU to work.

Modems that rely on the CPU are often designed specifically for the current version of Windows only, and will require drivers that are incompatible with future Windows versions, and may be difficult to upgrade. Software Modems are also very difficult to find drivers for non-Windows operating systems. The manufacturer is unlikely to support the hardware with new drivers after it is discontinued, forcing you to buy new hardware. Most such modems are internal or external USB, but this is not always the case.

Modems can be attached via USB, a traditional serial port, or an internal card slot. Internal and USB modems are more easily autodetected by the operating system and less likely to have problems with setup. USB and serial port modems often require an extra power supply block.

Gaming modems are normal modems that default to having a low compression setting to reduce lag, but are generally no longer used by gamers, who prefer broadband connections.

Ethernet card
An ethernet card is required in order to connect to a local area network or a cable or DSL modem. These typically come in speeds of 10Mbps, 100Mbps, or 1000Mbps (gigabit); these are designated as 10Mbps, 10/100Mbps, or 10/100/1000Mbps products. The 10/100 and 10/100/1000 parts are most commonly in use today. In many cases, one or two ethernet adaptors will be built into a motherboard. If there are none, you will have to purchase one - these typically are inserted into a PCI slot. For 10/100/1000Mbps ethernet, it is recomended that you use the adaptor built into your motherboard.

Peripherals
Your computer and you interact through the peripherals. The keyboard and monitor are pretty much the barest minimum you can go with and still be able to interact with your computer. Your choice in peripherals very much depends on personal preference and the complexity of the interactions you intend to have with your computer.

Keyboard and mouse
When choosing a mouse, there is generally no reason not to choose an optical mouse. They are considerably lighter (and as such, reduce RSI) as they have no moving parts, they are much better at smoothly tracking movement, and they don’t require constant cleaning like ball mice (though it may be wise to brush off the lens with a q-tip or other soft tool on occasion). Make sure that you spend money on a decent-quality mouse made by companies such as Microsoft or Logitech, as lower-end optical mice will skip if moved too fast. Mice of medium-to-high quality will track the movement almost flawlessly.

Although three buttons are generally enough for operating a computer in normal circumstances, extra buttons can come in handy, as you can add set actions to extra buttons, and they can come in handy for playing various video games. One thing to note is that with some mice those extra buttons are not actually seen by the computer itself as extra buttons and will not work properly in games. These buttons use software provided by the manufacturer to function. However, it is sometimes possible to configure the software to map the button to act like a certain keyboard key so that it will be possible to use it in games in this manner.

Wireless keyboards and mice do not have a very noticeable delay like they once did, and now also have considerably improved battery life. However, gamers may still want to avoid wireless input devices because the very slight delay may impact gaming activities, though some of the higher end models have less troubles with this. The extra weight of the batteries can also be an inconvenience.

Printer and scanner
For most purposes, a mid-range Inkjet Printer will be more than enough for most people, and you will generally want one that is capable of printing around 4800dpi, and you will also want it to be able to print out fairly quickly. When choosing a printer, always check how much new cartridges cost, as replacement cartridges can often outweigh the actual printer's cost in less than a year. Of course, double check extra information about the printer you are interested in (for example, Epson has protection measures that make refilling your own ink cartridges more difficult because the printer will not see the cartridge as full once it is used up).

For office users that plan to do quite a bit of black and white printing buying a black and white laser printer is now an affordable option, and the savings and speed can quickly add up for home office users printing more than 500 pages a month.

Scanners are useful, especially in office settings, they can function with your printer as a photocopier, and with software can also interact with your modem to send Faxes. When purchasing a Scanner, check to see how "accessible" it is (does it have one-touch buttons), and check how good the scanning quality is, before you leave the store if possible.

Finally, "Multi-Function Centres" are often a cost-effective solution to purchasing both, as they take up only one port on your computer, and one power point, but remember that they can be a liability, since if one component breaks down, both will need to be replaced.

Display
When choosing a display for your computer, you have two key choices of technology: the Cathode Ray Tube (CRT) screen, or an LCD screen. Both technologies have their advantages and disadvantages: CRTs are generally preferred by gamers and graphic artists, for both the price at which they can be bought and their generally superior response times, but this is offset by the added size and weight that a large screen requires. LCDs are generally more expensive than CRTs, but high-end models are generally preferred for tasks which need higher definition, such as movie editing, and are also popular amongst people with little-to-no desk space, as they do not need as much space as a similarly-sized CRT.

LCD panels
Liquid Crystal Displays (LCD's) have the advantage of being a completely digital setup, when used with the DVI-D digital connector. When running at the screen's native resolution, this can result in the most stable and sharp image available on current monitors. Many LCD panel displays are sold with an analog 15-pin VGA connector or, rarely, with an analog DVI-I connector. Such displays will be a bit fuzzy, and are generally best avoided for a similarly-sized CRT. If you want an LCD displays, be sure to choose a digital setup if you can; however, manufacturers have chosen to use this feature for price differentiation. The prime disadvantage of LCDs is "dead pixels", which are small failing areas on your monitor, which can be very annoying, but generally aren't covered under warranty - this can make purchasing LCD displays a financial risk. LCDs are generally OK for fast-paced gaming, but you should be sure that your screen has a fairly fast response time (of 12 ms or lower) if you want to play fast games. Nearly all flat panels sold today meet this requirement, some by a factor of 3. When picking an LCD, keep in mind that they are designed to display at one resolution only, so, to reap the benefits of your screen, your graphics card must be capable of displaying at that resolution. That in mind, they can display lower resolutions with a black frame around the outside (which means your entire screen isn't filled), or by stretching the image (which leads to much lower quality). Running at a higher resolution than your monitor can handle will either make everything on the screen smaller, at a significant quality drop, or will display only a part of the screen at a time.

CRT (cathode ray tube) displays
The other key type of display is the CRT or Cathode Ray Tube display. While CRT technology is older it often outperforms LCD technology in terms of response times, color reproduction, and brightness levels, although LCD displays are quickly catching up. There are two types of CRT displays, shadow mask and aperture grill. An aperture grill display is brighter and perfectly flat in the vertical direction, but is more fragile and has one or two mostly-unnoticeable thin black lines (support wires) running across the screen. CRTs are generally 2-4 times as deep as similarly-sized LCDs, and can weigh around 10 times as much, but this normally isn't a concern unless you will be moving your computer a lot. If you purchase a CRT display over the internet, shipping is much quicker, which is good for gaming, however, can cause headaches in some people at lower rates, so it may be ideal to pick a screen offering higher update frequencies at whichever resolutions you intend to use. Most people who have problems with low frequencies (60Hz) find it preferable to have at least 80Hz at the intended resolution. Some won't be bothered by this at all however.

Note that sometimes the CRTs with a flat screen instead of curved are called "flat screens" so this is not to be confused with the term "flat panel" used to refer to LCDs.

Speakers
Computer speaker sets come in two general varieties; 2/2.1 sets(over a wide range of quality), and "surround", "theater", or "gaming" with four or more speakers, which tend to be significantly more expensive. Low-end speakers usually suffer from low bass response or having no amplification, both of which make a huge difference in sound. Powered speakers with separate sub-woofers usually cost only a few dollars more and make a significant difference. At the higher end, one should start to see features like standard audio cables (instead of manufacturer-specific ones), built in DACs, and a separate control box. The surround sets are usually identical to the 2.1 set of a manufacturer, just with more speakers, which can be useful for gaming or movie watching. 5.1 and 7.1 support are becoming standard now, however, it is still necessary that you ensure your sound hardware is capable of 5.1/7.1 before buying a speaker system for this. If you have a lot of money you want to spend on audio, it may be wiser to avoid the computer speaker market entirely and look into piecing together a set of higher-end parts. The computer speaker market tends to start pumping up wattage without making any quality improvement - you can usually get more volume, that's all. If you are buying a speaker system designed for PCs, research the systems beforehand so you can be certain of getting one that promises clarity rather than just simple wattage. (Note: speaker power is usually measured in RMS Watts. However, some cheap speakers use a different measure, PMPO which appears much higher.)

Headphones can offer good sound much more cheaply than speakers, so if you are on a limited budget but want maximum quality they should be considered first. There are even headphones which promise surround-sound, though opinions on this are usually not good.


Assembly

Now that you have selected your parts, you get to what is arguably the more fun part of the process: putting the parts together.

Tools and equipment
There are a few tools that you will need to begin assembling your computer. The following is a good starting point, as they include the bare minimum to build a working computer.

Basic tools
Before you begin building or refitting a computer, you will need some basic tools:

#2 phillips-head (cross-shaped) screwdriver
Needlenose pliers
All available manuals for every component to be installed
Anti-static Wrist Strap (optional)
Grounding Mat or anti-static carpet (optional)

Optional, but useful tools
Some other tools and equipment can come in handy as well, such as:

Spring action parts grabber.
Electrical tape
Flashlight
A second, working computer to swap parts, look for tips, ask for help online, download drivers and patches, etc. - very useful
A can of compressed air - useful when working with older parts that have collected dust. A better alternative but also more costly, is a vacuum cleaner designed for cleaning electronics.

Preparation
Before you begin poking around inside your computer have the proper mindset. Read the instructions that came with your hardware. Do not work inside your computer if you are in a hurry or do not have the proper level of knowledge to complete the work. If you do not know how to do something reread the instructions, find futher information online, or simply ask some one who has more experience.

Find a dry, well-ventilated place to do your work. You should have plenty of light to see your components with, and if possible, you should choose an area without carpet on the floor, as carpet tends to attract a lot of static, and most of this can be averted by choosing a conductive floor surface. An unfurnished basement is a perfect work location.!

To assemble your components, you will need a basic toolkit. For this kit, you will need

a Phillips-head (cross-shaped) screwdriver
an anti-static wrist strap, for grounding yourself with (these can be purchased at your local electronic supply store) - this can often be a huge saving over the amount of money that you waste by destroying your components with static electricity. Do not be tempted to connect yourself directly to a tap or other grounded object with only a length of copper wire, if the machine is still plugged in and there is an electrical fault, the consequences could be fatal. Anti-static wrist straps have a high resistance, thus limiting any potential current flowing through your body to safe levels.
Unpack all the components, and put them on top of the anti-static bags they came in, as this will prevent stray static from reaching your components. (Note. Anti-Static bags conduct electricity on the external surfaces!) Make sure you read the following section, as it contains some important safety information.

Safety precautions
Dismantling electronic components such as your Power Supply or Monitor is an extremely dangerous thing to do - do not do it! They contain several high-voltage exposed components, and can cause you severe electric shock if you touch them, even when the unit is not plugged in. So, please, don't even think of trying.
Nobody except you is at fault if you shock your components with static electricity. Make sure that you take the precautions in the previous paragraph to ground yourself from static electricity, such as with an anti-static wrist strap or grounding mat. (Note: if you really must work on a computer and haven't got proper anti-static equipment, it is usually OK if you make sure that you don't move about much; are not wearing any static-prone clothing; handle components by the edges; and regularly (once a minute or so), touch a grounded object.). The case metal of your PC's power supply will usually be a suitable grounded object. As noted above, touch it every few minutes while you are working on your PC.
Please construct your computer in a dust free enviroment! The worst thing for components (besides static) is overheating, most commonly caused by fans and heatsinks clogged with dust. If this occurs, the fans will fail, and will cause your system to overheat and fail. However, if they are clogged, just buy a can of compressed air and blast the fans with it to clean them.
Unplug your PC's Power Supply before installing or removing any components - if power is flowing to components as they are installed or removed, they can be seriously damaged.
Never cut the grounding pin off your power cord. This "safety ground" stands between you and potentially lethal voltages inside the power supply.
Be wary of sharp edges! Many lower-end PC cases have sharp, unfinished edges. This is especially so on interior surfaces, and where the case has been cut or punched-out. Use care and take your time to avoid cutting your hands.

Construction
Start by putting your case down on your work surface, with the side opposite of the case door facing down, and open the case.

Motherboard
Try to find the motherboard standoffs that should have come with the case. They are screws with screw holes on the top.

Insert the standoffs into the holes on the motherboard plate in the case that correspond with the holes on your motherboard and screw them into the bottom of the case. Also remove the I/O Shield that came with the case, and put in the I/O Shield that came with your motherboard.

Some case styles make it difficult to install the motherboard or the CPU with the power supply installed. If the power supply is in your way, now would be a good time to take it out and set it aside (we'll put it back in later).

Insert the motherboard by placing it into the open case. The ports in the upper left hand corner should line up with the I/O Shield and go through the holes in it. The screw holes should line up with the motherboard standoffs. Put a screw into each hole in the motherboard with a hole below it.

Now that you have your motherboard in, you may plug in the other components.

CPU
 
An example of a CPU socket, Socket AAs installation of the different makes of CPU can differ between brands, it is generally safer to refer to the manufacturer's instructions, that are provided with the CPU. If you are using a thermal paste with your CPU, follow the directions that came with them for details on how to apply it.

The two things that go wrong the most often and most expensively (minimum of a killed CPU, sometimes more) in building one's own computer are both related to the CPU and its cooler:

Switching the computer on "just to see if it works" before adding any CPU cooling unit. Without cooling, CPUs heat up at extreme rates (a CPU heats up anywhere between ten times and a thousand times as fast as a cooking area on your stove!) By the time you will get the first display on the screen, your CPU will already be severely overheating and might be damaged beyond repair.
Mounting the CPU cooler improperly. Read the instructions that came with your CPU and cooler very carefully and ensure you are using all components in the correct order and correct place.
Make sure you get a cooler that is compatible with the CPU you have. Most brands come with multiple mounting brackets that will suit all different chipsets, but it's best to check for compatibility just in case.

If using thermal paste, apply it only to the CPU die (the square piece of silicon in the middle of the CPU) and do so sparingly -- most modern CPUs take no more than a grain of rice sized dab of thermal paste. Some people do like to wipe some onto the heatsink's surface and then wipe it smoothly off so that bits of it may get into tiny holes for better heat transfer. See Arctic Silver Instructions for more info on how to apply and remove thermal paste/grease. (It was written to be specifically for Arctic Silver paste, but the same techniques can be applied to other brands of thermal paste.)

If using a thermal pad supplied with your cooler, make sure you remove any protective tape just before installing and do not get it dirty - and do not combine thermal pads with thermal paste, it's either one or the other. Then, check that you install the cooler in the right orientation and that you set it flat on the CPU die without exerting undue pressure on any edges or corners - the latter can make small pieces of the die break off, killing the CPU.

One option you may consider, before installing the heatsink, is to "lap" the heatsink, which means to smooth out the bottom surface. To do this, start by sanding in smooth circular motions with a coarse grain sandpaper to smooth out the worst of the uneveness, then, as it starts to get smoother, switch to a finer grained sandpaper (the numbers go up as the sandpaper is finer, so something such as 60 is coarse while 220 will be very fine.) If you get it right, it should have a surface which feels completely smooth to the touch where you can almost see a reflection in it. Some companies producing heatsinks lap the surface themselves and this will be unnecessary, but, it is very rare. A lapped heatsink is far more effective due to having better contact with the chip.

Tighten the cooler using only the specified holding devices - if you did everything right, they will fit. If they don't fit, check your setup - most likely something is wrong. After mounting the cooler, connect any power cables for the fan that is attached onto the cooler. Then, if everything is seated tightly and firmly, you can safely run your first test, making sure the CPU fan does run (you have a few seconds of safety margin here, but if the fan is not running, switch off the system quickly, and then check your cabling.)

As an aside to the instructions above, it has been my personal experience that fitting the CPU and heat sink is best done on a supportive surface (a telephone directory on a table in my case) prior to installation, to avoid excessive flexing of the motherboard.

RAM

Next, you will need to install your RAM (random access memory). Start by pushing on the levers on both sides of the DIMM socket, so that they move to the sides. Do not force them too hard.

Put the RAM module in the socket. Line up the notch in the center of the module with the one in the center of the RAM socket, making sure to insert it the right way. Force the module until both levers go into the notches on both sides of the module. Although this does require a fair bit of force, do not over do it or you may break the RAM module.

Start adding RAM at "Bank 0" or "DIMM 1". If you don't start from "Bank 0" or "DIMM 1" the system will think there is no RAM and not boot.

On newer motherboards with 4 slots, you'll see alternating colors. For example, slot 1 is blue, slot 2 is black, slot 3 is blue, slot 4 is black.

If you were to put 1 gigabyte of RAM in your PC, it's best to use dual channel 512MBx2 chips. Put the first 512MB chip in slot 1, and put the 2nd chip in slot 3 (the two slots that are blue) - leaving slot 2 empty. This will give you better performance, vs. putting 1GB in slot 1, or two 512MB chips in slot 1 and 2.

Power supply
Some cases include power supply units (PSUs) that are already installed. Some of these are underpowered or of lower quality, especially in inexpensive case/PSU bundles. Before purchasing or installing any PSU, make sure that the supplied wattage is sufficient for your components. Power requirements are usually listed in the manuals that came with your components. It is important to note a power supply's total power, and the power at each voltage: 3.3, 5 and 12V. If any of these do not meet your requirements, the rest of the specifications don't matter.

Some companies have calculators to help you determine what your power supply needs are; if you are the type to just plug in the numbers without reading the details, you should buy a power supply that is 1.5 to 2 times the wattage that results from these calculators.

Power Supply Calculators

The JourneySystems Power Supply Calculator http://www.journeysystems.com/power_supply_calculator.php

The eXtreme Power Supply Calculator v2.0 http://www.extreme.outervision.com/psucalculator.jsp

Video card
If your mother board has a built-in video adapter you want to use, skip this section.

If you have an AGP video card: Install the video card into the AGP socket. This is always the top expansion slot near the back of the computer. AGP slots are often brown, but can also be strange colours such as fluorescent green. Check the motherboard for levers (or similar devices) that are part of the AGP slot to help hold the card in place. These must be retracted before insertion of the card. Check the motherboard's manual for information on how to use these devices (if your motherboard has one.) Push the card into the socket (AGP slots are often pretty tight, don't be afraid to push it until it's well inserted), then screw it in at the top of the metal bracket. If it has a power connector, connect it to a 4-pin molex connector. If it has a pass through, do not connect it to a hard drive.

If you have a PCI Express video card: Put this in the same way as a AGP video card, however the slot where it goes looks a little different than the AGP slot. It will look like it but have an extra spot on the slot as opposed to the 2 slot parts on an AGP slot. PCI Express is 16x meaning it can handle the transfer of twice as much data as AGP 8x.

Installing drive jumpers
Each SATA connector can only handle one drive, so there is no need to adjust jumpers -- you can skip this section. Before you install IDE/ATA drives, you will need to set the drives jumpers. Each IDE/ATA channel can handle two drives, a master and a slave. Consult your motherboard/drive's instructions on how to set the jumpers. The jumper configurations are usually either printed on the back, or on the top of the drive. Drives can be configured in 2 ways: Drive Select or Cable Select.

"Cable select": Use this if you have 80-pin cables. Cable select automatically assigns slave/master based on the plug on the IDE cable the drive is plugged into. Put the jumper on CS.
"Drive select": If you are using a 40 pin cable, you must use "drive select". master/slave is determined by the jumper. In this mode, configure one of the drives the master, and the other slave. If the IDE channel has only one drive, check your motherboard documentation for the appropriate setting, which is usually master.

Installing drives
Next install the hard drive and optical drives.

How a drive is installed will depend on the case.

When using an IDE cable, plug the two connectors that are closer together into the 2 drives, and the third to the controller or motherboard. The connector furthest from the board should be attached to the Master drive. Make sure the drive that you will install your OS on is primary master. (Note: IDE connectors are keyed, so it should be impossible to insert them backwards. However, it doesn't require very much force to do this, and you may destroy your motherboard if so. Also look carefully at the drive and the cable connection before you try to connect them. You will probably see a "missing" pin on the drive, and a corresponding blocked socket on the connector. If you break a pin on the drive, you will probably have a worthless drive. Note: most parallel IDE cables have a colored stripe down one side. That colored stripe signifies "pin 1" - and usually will line up next to the molex power connection on your drive. Use this rule of thumb if your connectors aren't keyed.) Next, plug a 4 pin molex power connector into each hard drive and optical drive. If you are installing the power connector to a SATA drive, only install one of the power connectors. Some drives have the option of using either the SATA power connector (a flat about 1" wide connector) or the standard molex connector; use one or the other, not both. Make sure the IDE cables are in the proper slots - usually, you should mount the master drive in slot 1, and any slave drives in the other IDE slots. For better data transfer, you can purchase heat-protected high-end data cables at your nearest electronics store.

If you install a floppy disk drive, the cable is very similar to the IDE cable, but with fewer wires -- and a strange little twist in the middle [ need photo here ]. Floppy drives do not have master/slave. BUT the floppy disk connector is not usually keyed, making it all too easy to plug it in the wrong way! One wire in the IDE cable will be coloured differently: this is pin 1. There is usually some indication on the floppy drive as to which side this is. The power plug for a floppy is 4 pins in a line, but rather smaller than the standard hard drive power connector. Plug the end of the cable with the twist into the floppy drive ("drive A:"). Plug the other end of the floppy ribbon cable into the motherboard. If you install a second floppy drives, plug the middle connector into "drive B:". The twist between drive A: (on the end) and drive B (in the middle) helps the computer distinguish between them. [1]

Expansions and connections
Now, install any PCI cards that you have. These generally include sound cards, network cards, video cards, and TV tuners. These fit into the white slots that are just below your AGP/PCI-E slot (if your motherboard has one).

Also plug in any power cords, including the 20pin and the 4 pin cords that you haven't plugged in yet. Before you finish up and power it up, you need to connect the power/reset buttons and front panel lights. The plugs from the front of the case will be labeled. The pins on the motherboard may be labeled, but they will be difficult to read because they are small. The foldout that came with the motherboard tells where to connect these connectors. The front panel LEDs are polarised: usually the positive wire is white.

In addition, you can optionally connect any case-specific port if it is supported by the motherboard. Some common examples include USB ports and sound ports.

Next, close the case and take your computer to where you will be using it. Plug in the power cord, mouse, keyboard, monitor, and any other peripherals you may have to the computer.

Power up
Press the power button. If smoke appears (it shouldn't, unless your power supply or cooling systems are insufficient), or if the computer doesn't do anything, unplug the power cord immediately and check the steps above to make sure you haven't missed anything. Give special attention to the cables and power connections. If the computer does appear to come on, but, you hear beeps, listen carefully to the beeps, turn the computer off, and refer to your motherboard's manual for the meaning of the beeps. Some boards have an optional diagnostic device, usually a collection of LEDs, which when properly plugged in will inform you of the nature of the problem. Instructions for installing this as well as the meaning of it's display should be in the manual for the motherboard. If it turns on but the only thing that comes on is your power supply, turn off your computer. This probably means something is shorted, and leaving it on could damage the parts.

At this point, you will wish to set certain options in the Computer's BIOS (usually by pressing 'F1' or 'Del' a few seconds after boot.) These options will be explained in the motherboard manual. In general, the default options are OK, but you may wish to set the computer's hardware clock to the correct time and date. The BIOS is also where you determine the default boot order of the system, typically Floppy, then CD-ROM, then Hard Disc.

If you want a further quick test, before you install an operating system, you may find a bootable CD-ROM such as Knoppix extremely useful.

Peripherals
 
Comparison of VGA and DVIYou may also need to install peripherals such as keyboards, mice, speakers, monitors and extra devices like printers. Each of these comes with a connection cable and software to control them (driver). There are two standard connectors for mice and keyboards; PS/2 connectors and the more modern USB connectors. (Look at the images to see which one yours are) . Plug the mouse and keyboard in the appropriate slot.

Note: If you intend to install an operating system from a boot CD or floppy, or modify bios settings you will need to use either a PS/2 keyboard, a USB to PS/2 converter, or a motherboard that supports USB devices. Otherwise your keyboard will not work until the operating system has loaded USB drivers.

To plug in speakers, you need a sound card, which is preinstalled in most motherboards. The speaker plug will probably be a standard 3.5mm plug, just like headphone plugs. Since speaker sockets and microphone sockets are the same type, they are often colour coded. Green usually represents speakers and pink represents microphones. In most cases, a third plug is present - this is the input channel which allows the sound card to receive an audio signal from another device, such as a Hi-Fi system.

Monitors will either have a VGA or a newer DVI plug (see picture, as they are a lot less apparent than PS/2 / USB comparision). Most monitors use VGA connectors, and so most graphics cards have VGA output. If you have one type of plug and the graphics card has another, you can easily buy an adapter.

Most other devices use USB connectors, so follow the instructions on the CD you were given with them.

 


Choosing and installing the software

Regardless of whether your computer is a brand name system or one that you built yourself, it will need software. This may come preinstalled on the hard drive, but more than likely you will need to install this yourself. If you make informed decisions and select the right pieces of software you can avoid many hidden costs that are often charged to your computer. Installing operating systems (OSes) and software to your own specifications can greatly improve performance.

This section will attempt to explore the key options that you have when setting up your computer for use.

Operating system(s)
The first thing to do after you have a working PC is install an operating system (OS). You can select from several available on the internet or from your local computer store. The first option, and the one taken by most people, is to just install Microsoft Windows, of which the current version is Windows XP. Another option is to install a Linux distribution (a Free Software operating system). There are many other operating systems to choose from as well, notably the very famous Linux but let us not forget the other free open source operating systems, such as BSDs. Note that you also have the option of installing more than one operating system in what is called a multiboot setup.

If you are going to install both, install Windows XP first. This is because Windows overwrites the software that Linux requires to start up, even if something's already there. If you install Windows before all of your other systems, you will be able to easily boot into all of them.

Choosing between Microsoft Windows, Linux, or one of the other operating systems is largely depependent on user needs. Simply put, can you accomplish your day to day task with the sofware associated with the operating system installed in your system? Microsoft Windows is better in terms of software availability and support, but Linux wins in terms of stability, ability to run on older equipment, and cost. Both systems have a range of software, but determine your needs before installing either operating system.

Installing Windows
The installation of Windows is relatively easy. Push the button on the front of the PC, put the CD-ROM in your optical drive, and follow the on-screen instructions. Partitioning the hard disk(s) is different if you are dual-booting or going with just XP. If you are doing a Windows-only install, just allocate all of the hard drive to XP.

If you are dual-booting, some extra considerations must be taken. NTFS, which is the default filesystem that Windows uses, is not very well supported outside of Windows. GNU/Linux support is up to the point where it can read, but not write, an NTFS filesystem. However, it does have some advantages over FAT32, in that a 4GB file size limit no longer exists. Likewise, Windows has no support for any of the standard Linux filesystems. If you are going to be switching between the two frequently, then it might be in your best interest to create a FAT32 for both operating systems to use.

When it comes the time to partition the hard disk(s), remember to leave space for Linux (if you're installing it - a good amount is somewhere in the order of a third of your total hard disk space). You may want to have a spare FAT32 partition (of around 1 third of your disk space), on which to share documents between Windows and GNU/Linux, as Linux's support for NTFS disks is good, but not perfect. You should also modify the table as necessary - you may not need as much space for Windows or you may need more in your FAT32 transfer area. But you must ensure that you leave at least 3GB for your Windows installation, since the standard installation of Windows takes up about 2 GB of hard drive space, and it is always wise to leave a bit extra on, to allow for any changes that may occur.

Some people find that it's useful to create separate partitions for the operating system and data. This means that if something goes wrong with the operating system, the partition can be formatted and the operating system can be reinstalled without possibily losing data.

If you are installing Windows on a RAID drive, or a SATA drive in most cases you are going to have to provide the Windows installer drivers to access the hard drive on the raid controller. To do this while Windows install is at the blue screen, at the bottom it will read "Press F6 to install any third party SCSI or RAID drivers." Later during the install it will come up with a screen says "Setup could not determine the type of one or more mass storage devices installed in your system, or you have chosen to manually specify an adapter." At this screen you are going to want to hit 'S' to "Specify Additional Device," another screen will pop up asking you to insert the floppy disk containing the drivers, followed by a screen asking you to choose the appropriate driver out of the set contained on the disk (most disks will have a for each of the major Windows operating systems).

Installing GNU/Linux
See also: Linux Guide
See also: Wikipedia:List of Linux distributions
See also: Wikipedia:Comparison of Linux distributions
The primary problem faced in installing Linux is choosing between distributions. Of the many variants of Linux, SuSE, Fedora and Debian are generally recommended, as they are updated regularly and compatible with a broad range of hardware:

SuSE, OpenSuSE 10.1 best GNU/Linux distribution, SLED 10 and SLES 10 for the enterprise desktop and servers.
Fedora Core, currently at version 5. Used to be the de facto-standard of good GNU/Linux.
Debian, another famous distribution, but much harder to install.
Some GNU/Linux variants may support hardware that these do not. If you have obscure or old hardware, you may want to search bulletin board sites for various GNU/Linux variants to ensure compatibility. For my purpose, I will pick Ubuntu, which the current standard of ease-to-use GNU/Linux. One can download the .iso image or order a CD set (containing the installation CD and LiveCD) from its website. An .iso is nothing more than a special file format that your cd drive buring software uses to create a copy of the software, in this case a copy of Unbuntu GNU/Linux. The installation of Linux is relatively easy. Push the button on the front of the PC, put the CD-ROM in your optical drive, and follow the on-screen instructions. By default, the installation version of Unbuntu will erase all files on the hard drive and partition 1.8 GB for the OS. If one wants to customize, follow the on-screen instructions carefully. The LiveCd version does not erase your harddrive and is intended solely for a user to test drive Unbuntu Linux, because of this it is the preferred choice in determining whether or not you wish to continue with a full installation.

Security
After installation, your priority should be security.

Updates
From time to time, software companies and independent programers release new and improved versions to their software; these are known as updates. Updates usually install new features or fix problems, present or not present in the previous version. Usually, the computer user should download the latest updates to improve system performance. Many program programs update themselves, this process is know as an automatic update. If you have to manually update your software, do so through the software developer's site, not through a secondary source. This approach will reduce the chance of contracting a virus or other piece of malicious software.

Windows
A newly installed Windows XP computer using a broadband connection can be attacked within moments of being connected to the Internet. In severe cases, the attacks can render a system unbootable or make a second reinstallation faster or easier than manually removing the malicious programs causing the problems. The SANS Institute provides a PDF guide called Windows XP: Surviving the First Day, which explains how to update a new Windows XP box without immediately becoming infected by viruses and worms. To avoid having your new computer attacked, install a firewall, or activate the one that came with your OS. Both Windows and Linux have in-built firewalls: In some Linux distributions, it is enabled by default; in Windows XP Service Pack 2, it can be found in the program in your control panel.

As soon as you are on the Internet, run your operating system's update facility to fix any security flaws that have been found since your CD was printed. To do this under Windows, simply click on your Start Menu, click on 'All Programs', and then click on Windows Update, and follow the instructions. If you use other Microsoft products, such as Microsoft Office, then it can be valuable to use Microsoft Update, which covers updates for all Microsoft products. For either of these, you can also switch on "Automatic Updates" from the Security Center program mentioned above.

GNU/Linux
The method of updating your GNU/Linux system varies greatly from distribution to distribution.

For SuSE, there are two ways:

YaST
ZENworks updater
For Fedora, type

yum update
as the root user inside a terminal window.

It is perhaps easiest to update the OS from Debian-based distributions such as Debian, Ubuntu and Linspire. For Debian and Linspire you type the following into a terminal window while running as the root user:

apt-get update
apt-get dist-upgrade
Ubuntu has you run sudo to switch run a program as root. Type the following into a terminal:

sudo apt-get update
sudo apt-get dist-upgrade

Automatic updates
If your computer will be running overnight, it may be good to have your computer update itself.

Debian based cron-apt
Windows Windows Update

Anti-nasty
Programs such as Anti-Virus, Anti-Spam and Anti-Spyware of commercial quality or better can be found quite easily: Windows programs are listed in the software section below. (Usually these are not needed for non-Windows OSes)

An important point to note is that security software is one of the more important things to be set up rather than other applications first. In one case, a freshly-assembled computer running Windows XP with no security precautions taken was hit by the Blaster worm as soon as it was connected to the Internet, and has picked up a variety of spyware after only visiting a few websites; forcing the owner to reformat the hard disk and redo installation of the OS.

Drivers
Now that your computer is relatively secure, you will need to install software to control your various hardware components. This type of sofware is known as a driver.

Although, most of your hardware will come with a cd containing the necessary driver, it is generally a better idea to download the driver straight from the company's Internet site. This will insure you have the lastest edition of the software complete with a minimal or no known software problems. Knowing where to download the driver is also good in the case you lose the cd that came with the device. If you do not have a fast internet connection (broadband), the company usually provides an option to receive the driver cd in the mail. Even if something seems to be working fine, downloading new drivers may help increase computer effiency. Downloading drivers for your motherboard's chipset can often help. Finally, many monitors will not go above a certain refresh rate without its driver, which may be of great concerns to gamers.

If you are using Microsoft Windows, you can generally find drivers for your selected hardware on the manufacturer's website. Most Linux systems already have all of the drivers installed, with the exception of proprietary modem and graphics drivers. If you can't find your required driver, a simple Google search will yield the best results.

Software
Finally, load it with some good quality software. The majority of programs to meet your day to day needs, are available for free. It should be noted that cramming your hard drive with all the software out there is a BAD IDEA and decreases your computer's efficiency. Please, only install software that you actually need for your computer. Also, before installing any piece of software make sure you have backed up your hard drive.

There is free software for all current operating systems used by the general public, including Word Processors, graphics application, email clients, and Anti-Virus software. The following are recommendations for each operating system:

Windows
Web Browser: Mozilla Firefox or Opera (Opera is usually faster on slower hardware and works better on older versions of windows).
E-mail Client: Mozilla Thunderbird
Office Suite: OpenOffice.org
Disc Tools: CD Burner XP, Burn at Once
Instant Messenger: Gaim, Trillian, Miranda
Media Player: DivX Player, Nullsoft Winamp, iTunes, SnackAmp
Anti-virus: AVG Anti-Virus, Free Edition, avast!Antivirus Home edition, ClamWin
Security: Spybot: Search & Destroy, Ad-Aware Personal Edition, K9 Anti-Spam,ZoneAlarm Free Edition
Compression: 7-Zip, IZArc, TUGZip
Desktop Search: Google Desktop

GNU/Linux
Unlike with Windows, on a GNU/Linux system the majority of the software that you will want for your computer is already included. You will probably not need to download anything. Most GNU/Linux distributions have a package manager (Portage for Gentoo, APT for Debian-based distros like Debian and Ubuntu, etc.) For some distributions, simply download RPM or DEB files from your distribution's web site.

If they aren't already installed by your distribution:

Web Browser: Swiftfox or Opera (Opera is usually faster on crappy hardware).
EMail Client: Mozilla Thunderbird.
Office Suite: OpenOffice.org or AbiWord
Instant Messenger: Gaim or Kopete.
Media Players: Rhythmbox, mpd, amaroK (depending on what desktop environment you use), Beep Media Player or Video Lan Client.
Movie/DVD Player: Xine or MPlayer.
Windows Compatibility Layer: Wine.
x86 Emulator: QEMU.
PPC Emulator: PearPC.

Additional Software
For additional software some excellent sources of free and open-souce software are

Tucows a downloads site with freeware, shareware, open-source as well as commercial software. It has many mirrors all over the world for speedy downloads from local servers.
Download.com similar to tucows
SourceForge a site featuring many OpenSource projects. You can start your own, or get software for almost every need. Most projects have GNU and Windows versions. The mirror system isn't as large as Tucows, but you can still usually get a mirror on the same continent.
Table of equivalents can be usefull if you want to know more about specific programs when changing from windows to GNU or vice-versa.


Optimizing and overclocking

Overclocking
Overclocking is the practice of making a component run at a higher clock speed than the manufacturer's specification. The idea is to increase performance for free or to exceed current performance limits, but this may come at the cost of stability.

Think of the 3GHz on your new 3GHz Pentium 4 as a speed limit asking to be broken. This can be done to several components in your computer. This often takes advantage of the fact that many manufacturers mark higher end components as lower in order to meet demand for a lower end component. You will be able to get extra performance out of your components for free. It is possible to get performance that is not possible even when using the top of the line components. And you can buy cheaper parts, and then OC them to the clock speed of the higher end component.

WARNING: OVERCLOCKING WILL VOID THE WARRANTY ON THE PARTS BEING OVERCLOCKED. DOING SO MAY ALSO CAUSE SYSTEM INSTABILITY, AND MAY ALSO CAUSE DAMAGE TO COMPONENTS AND DATA. BE CAREFUL AND CAUTIOUS WHEN OVERCLOCKING.

Things that can't be overclocked
Although it is possible to overclock many of the components of a computer (such as the CPU, FSB frequency and video card), it is not possible to overclock some components. For example, it is not possible to increase the read/write speed or access time of a hard disk or CD-ROM drive. The only solution to improving the performance of these components is to use faster components in the first place, or in some special cases of hard disks, change the configuration to a RAID. Many OEM computers have the CPU frequency locked. (But you wouldn't be reading this guide if you're using an OEM computer, would you?)

Components

CPU
The CPU's clock speed is the FSB clock speed (base, not effective speed) times the CPU's multiplier. On most newer CPUs, the multiplier is locked, so you will have to adjust the FSB clock speed (However, it might be possible to 'unlock' the chip's multiplier on some older chips. See CPU Locking.) The FSB is not adjustable on a few motherboards, and many OEM systems. The FSB and multiplier, if not locked, are adjustable from within the BIOS. Note that upping the FSB clock speed also increases the clock speed of many other components, including RAM. When increasing the FSB clock speed, only do so in small increments of a few MHz at a time. After you do this, boot up your computer to make sure it works. If your computer successfully boots, increase the FSB some more. If it won't boot, lower the FSB until your computer properly boots up. Repeat until you have the highest setting with which your computer will boot up. Next test your OS to make sure it is stable with a burn application, or any application that uses 100% CPU power. If a crash or reboot results, lower the FSB speed some more until it runs smoothly. On some motherboards you are also able to change the voltage of the CPU and other components in order to help stabilize the system. However, this increases the components' heat output and can harm or shorten the life of your system instead.

Notes: On AMD K8-based chips (Athlon 64, Opteron, Turion, and Socket 754 and 939 Semprons), there is no FSB- there is an integrated memory controller (IMC) and a HyperTransport bus (HTT). The IMC has a base clock speed like a FSB does and for overclocking, it would be adjusted just like a FSB would. The HTT can also be overclocked like the CPU core can be. Its base clock speed is the exact same as the IMC's and thus by default you will overclock the HTT bus as you overclock the CPU. Note that the HTT bus has a multiplier and it is adjustable. Many motherboards do not function well with the HTT bus frequency much over the stock frequency- that's where the adjustible HTT multiplier comes in. (It should be noted that overclocked systems are most stable when the HTT is at or below 1000Mhz)

Also, some newer desktop processors (AMD K8 series with Cool 'n Quiet, Intel Pentium 4 6xx series, Pentium D 830, 840, stepping C1 Pentium D 9xx series with Enhanced Intel Speed Step) and most mobile processors (exc. Celeron M) can vary their operating frequency while running by lowering the CPU multiplier. This results in the multipliers below the highest one being unlocked. This allows for a very high FSB/base clock speed with a lower multiplier to use very fast RAM to its full potential without overclocking the CPU so much that it is not stable.

How to choose the best CPU for overclocking
Assuming that you have selected quality components like an excellent motherboard, high-quality RAM , an excellent thermal solution and an excellent power supply; you may wonder why your processor won't exceed a certain speed limit. Lets assume that you have a memory chip that is capable of taking the maximum frequency the motherboard can throw at it and yet, when you exceed a certain speed limit you realize that your system becomes unstable.

A PCI bus generally runs on 33 Mhz. When you exceed 35-36 Mhz, the hard disk and other IDE devices become unstable, because the IDE controller is controlled through the PCI bus. Oftentimes, you may encounter texture corruption, when your AGP bus exceeds a certain speed limit. This was often observed on older motherboards that wouldn't allow you to lock the AGP and the PCI bus at stock speeds. The good news: Immaterial of the FSB speed, most motherboards nowadays automatically ensure that the frequency of the PCI, AGP and other buses always remain constant (in other words; their speeds are locked unless you deliberately change them). This implies that the other components connected to the motherboard don't undergo stress. You have ensured that you have the fastest memory chip and the obscenely fast speed ratings on your memory chip ensure that you can extract the most by bumping up your FSB to the limits. The main culprit that is plays the spoilsport is your CPU. I'll explain: So even if you have an exceptionally good thermal solution, your CPU won't exceed a certain limit. Example: I had experimented with a Pentium III 700E Mhz processor and a Pentium III 800E MHz processor on an Asus CUBX-E motherboard using Kingston PC-133 SD-RAM. The reason I chose these 2 processors for experimentation was because they both used a FSB speed of 100MHz. This motherboard was really flexible, I was able to increment the FSB to 150Mhz. I was able to extract 1050 MHz from the stock 700Mhz. This is because the multiplier is 7, which unfortunately cannot be changed. So I bumped up the FSB from 100Mhz to 150 Mhz; which gave me the resultant speed of:

7
(Multiplier) 150
(Front Side Bus) = 1050 MHz
(resultant frequency)

Simple arithmetic? Yes. Now, logically speaking, if I can extract 1050Mhz from a 700Mhz processor; I should be able to extract 1200Mhz from an 800 MHz processor. This is not true. I tried doing exactly the same with the 800 MHz processor and the Computer crashed. However, it was stable when I set the FSB speed on a 133 MHz. When I set the FSB at 133 MHz ; this was the result:

8
(Multiplier) 133
(Front Side Bus) = 1064 MHz
(resultant frequency)

This simple experiment simply shows that a CPU gets saturated after a certain clock speed. Typical symptoms of an erratic CPU include instability and at times, you may not be able to boot up at all.

This particular CPU die was manufactured using a 0.18u process. When Intel launched a similar CPU using a 0.13u process; they shipped those CPUs with the stock speed of up to 1.4Ghz. This CPU core was based on the P6 Architecture and it used a 10 stage pipeline. Presently, Intel manufactures the Pentium-M CPU which is based on the P-6 architecture; difference being that they manufacture it using a 0.09u process and they have increased the depth of the pipeline.

These terms may seem cryptic and this concept may be difficult for some to grasp. So why would I publish something so difficult?The answer is simple: It is not difficult at all. To be a successful overclocker; you need to purchase the best CPU possible; not necessarily the fastest. Always go for a processor that uses the latest manufacturing process. A CPU rated at 3Ghz which is manufactured by using a 0.13u process won't overclock as well as a CPU that is rated at 2.6Ghz using a 0.09u process.

Deeper pipelines ensure that the CPU has the capability to scale higher in terms of speeds. The disadvantage is that a CPU with a deeper pipeline is slower than a CPU that uses a smaller pipeline assuming that they are running at the same speed). AMD Athlon CPUs are famous for their relatively short pipelines. Thats why they perform better than the Pentium 4 CPUs at the same clock speed. Before purchasing the fastest processor, always keep this in mind. Choosing a processor smartly helps you extract maximum out of your machine. You don't need to know what a pipeline exactly does. Refer to the processor spec sheet, find out these basic details of the CPU core and its architecture and choose accordingly.

Video card
Two different parts of a video card may be overclocked, the GPU (Graphics Processing Unit) and the RAM. In addition, disabled pipelines on a video card may also be enabled through third-party drivers, third-party software, or direct hardware modifications depending on your video card type. Overclocking a video card is usually done through third-party or proprietary software.

Recent ATI proprietary Catalyst drivers feature an interface called Overdrive that allows for dynamic GPU frequency scaling based on its temperature and load. Increase the load, the clock rate increases for performance, but it's balanced against the increasing temperature. Sufficient for simple increases in overall performance, but doesn't allow for the best performance increase which requires overclocking the memory. For this you need third-party applications or drivers. An example is ATITool. This program has many options, including GPU and memory overclocking, temperature monitoring, and fan control allowing for a much more complete solution to overclocking ATI based video cards. As for example drivers, for ATI there are many, omegadrivers.net is one of them, also hosted there are nVidia drivers as well. Both of which include integrated overclocking and many unlocked features, even including enhanced image quality for nVidia-based cards. nVidia video cards can also be OCed through a hidden feature in the driver called coolbits. Coolbits is a feature that can be unlocked by downloading a set of regkeys, it is a good overclocking tool as it has a fairly conservative "optimal clock" once you have this increase the core clock (not the memory clock!!) then run a gpu intensive task like 3dmark, repeat until you have a sudden drop in the benchmark score. This is the thermal throttling kicking in, do not push it any harder as it will result in permanent damage to your gpu. Back off the clockspeed by about 20-30mhz.

The most important thing to remember about overclocking a video card is cooling. This can't be stressed enough. Just the same as a CPU can be damaged or have a shortened lifespan by overclocking or excessive and prolonged heat, so can a video card. In the past year many inexpensive and easy to install options have surfaced for cooling a video card, from adhesive ram heatsinks to attach to un-cooled ram chips, to rather expensive water-cooling solutions. A good midpoint (both in cost and effectiveness) solution is to purchase and install a direct exhaust, "sandwich" cooling solution. Direct exhaust means all air from the cooling fan is blown across the video card and directly out of the computer case, usually using the open PCI slot below the AGP (or PCIe) slot. This allows for substantially lower GPU temperatures. A sandwich cooler is two aluminum or copper heatsinks, shape formed for a particular video card, that "sandwiches" the video card in between the two and are usually connected by some kind of copper heat pipe which allows for the hotter side to convey heat to the cooler side for dissipation. The GPU should never surpass 60 degrees celsius for optimal performance and to avoid damaging the card. Most of the latest video cards are rated to go up to 90c, but this is NOT recommended by anyone. The optimal temperature for a video card is 40-55c for the card itself (the GPU's temperature differs depending on which you have,) but the lower you can get it, the better.

One important thing to note. Many think that the option which says "AGP voltage" in their BIOS can be used to "voltmod" a video card to get a bit more power out of it. In fact, it's used for something else, and raising the AGP voltage can and probably will cause damage to a video card.

Getting the few extra MHz out of a chip

Cooling
When increasing the speed of any computer components you are making the components work harder and by doing so they output more heat. Heat can cause system instability so cooling is necessary to help keep your components stable at higher speeds. Without good cooling you could harm or shorten the life of your system. CPU temperature can usually be checked from within the BIOS. However, these are inaccurate as your CPU is under almost no load in the bios. SiSoftware Sandra may be used within Windows to check temperature. This should be done when your CPU has been under a heavy load for a while for optimum results.

There are three types of cooling that are generally accepted for overclocking: Air, water, and peltier.

With both air cooling and water cooling some type of transfer material is needed to move the energy away from the sensitive electronics. The device used for this purpose is a heatsink. The two most popular heatsink materials are Aluminium and Copper. The heatsink that is stock on factory computers by major manufacturers (Dell, Gateway, IBM) is usually made of aluminium, which has satisfactory heat transfer characteristics. However when overclocking more heat is being produced from the increase in power consumption and in order to obtain lower tempertures a material with better heat transfer properties is important. For this reason Copper is the material that offers the best ratio of price/performance.

Power
Chips at higher speeds may need more power. Raising the vcore voltage on a CPU might enable it to go at slightly faster speeds but by doing so you add a lot more heat output from the CPU. The vcore of a processor is the voltage at which a chip is set to run at with the stock speed. This voltage may need to be changed when the multiplier is raised because otherwise the transistors in the chip wouldn't switch fast enough - transistors switch faster, the higher the supply voltage. If there is not enough voltage then the chip will begin to make mistakes and give bad data results. Good cooling is needed to keep the system stable at higher speeds. Raising the vcore too much may harm or shorten the life of your system. Raising the vcore can also greatly affect the stability of the system. This is where a high quality PSU will come into play. While many cheap, no-name brand PSU's will crash and die with more vcore, a good quality one will live to serve you for a long time.

Note: increasing the speed (multiplier or fsb) without changing the voltage will also increase heat output, but not as much as when also increasing voltage. Having said that, increasing the multiplier or fsb without adjusting the voltage may make your system unstable (undervolt).


Conclusion

Congratulations! If you've got this far through the book, you must have done something right. You now have a computer built entirely to your own specifications, budget, and personality. You've learnt more than is possible to learn from reading any PC Hardware book.

You have a new computer. Great. But it won't always be new. Here are some tips to keep it looking as shiny as ever:

First, always try to look for good deals. If you see a computer part for a good price, think about it, because it is always easier to spread the cost of upgrading a computer over a long time. Although, there is no reason to go overboard and always be on the cutting edge (unless you like playing high-end computer games such as Doom 3 or Half-Life 2).

Second, remember to keep updating your software. Log on to the internet regularly and update your:

Virus checker: This is important. An unprotected computer is not good. Loss of data, random hardware crashes and incredibly annoying glitches can all be the result of viruses.
Operating system(s): Update your operating system regularly to download patches for holes which viruses may enter your computer by, new features, and other cool stuff.
These two tasks can be scheduled to run in the middle of the night. Just remember to leave your internet connection on.

Third, occasionally (every two or three months is plenty) unplug your computer from the wall, take off the side panel, and blow out the dust with a can of compressed air, making sure to clean out the power supply as well. Be sure to not just relocate the dust from one part of the system to another but to actually blow it out. Doing this will improve the airflow inside your PC, lower the temperature, and thus give the computer a longer life. Not doing this can cause some components (such as power supplies) to eventually break a lot sooner than you were prepared for.